Optimize code structure for input module.

Assets/Cryville/Common/Unity/Input/UnityKeyHandler.cs

@@ -9,19 +9,19 @@ namespace Cryville.Common.Unity.Input {
 
 		public UnityKeyHandler() { }
 
-		protected override void ActivateImpl() {
+		protected override void Activate() {
 			receiver = new GameObject("__keyrecv__");
 			recvcomp = receiver.AddComponent<T>();
 			recvcomp.SetCallback(Feed);
 		}
 
-		protected override void DeactivateImpl() {
+		protected override void Deactivate() {
 			if (receiver) GameObject.Destroy(receiver);
 		}
 
 		public override void Dispose(bool disposing) {
 			if (disposing) {
-				DeactivateImpl();
+				Deactivate();
 			}
 		}
 
@@ -44,7 +44,7 @@ namespace Cryville.Common.Unity.Input {
 
 	public abstract class UnityKeyReceiver<T> : MonoBehaviour where T : UnityKeyReceiver<T> {
 		protected Action<int, int, InputVector> Callback;
-		protected readonly List<int> Keys = new List<int>();
+		protected readonly HashSet<int> Keys = new HashSet<int>();
 		public void SetCallback(Action<int, int, InputVector> h) {
 			Callback = h;
 		}